Some of the 300,000 computer-controlled mirrors, each about 7 feet high and 10 feet wide, reflect sunlight to boilers that sit on 459-foot towers. The sun's power is used to heat water in the boilers' tubes and make steam, which in turn drives turbines to create electricity Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Photo: Chris Carlson, AP

Some of the 300,000 computer-controlled mirrors, each about 7 feet...

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HOLD BY STORY SLUGGED: Solar Power Rising BY MICHAEL R. BLOOD and BRIAN SKOLOFF -- Noel Hanson stands near some of 300,000 computer-controlled mirrors that reflect sunlight to boilers that sit on 459-foot towers near a boilers that sit on 459-foot towers Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles. (AP Photo/Chris Carlson)

Photo: Chris Carlson, AP

HOLD BY STORY SLUGGED: Solar Power Rising BY MICHAEL R. BLOOD and...

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Some of the 300,000 computer-controlled mirrors, each about 7 feet high and 10 feet wide, reflect sunlight to boilers that sit on 459-foot towers. The sun's power is used to heat water in the boilers' tubes and make steam, which in turn drives turbines to create electricity Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Photo: Chris Carlson, AP

Some of the 300,000 computer-controlled mirrors, each about 7 feet...

Image 4 of 10

Image 5 of 10

Some of 300,000 computer-controlled mirrors reflect sunlight to boilers that sit on 459-foot towers Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Photo: Chris Carlson, AP

Some of 300,000 computer-controlled mirrors reflect sunlight to...

Image 6 of 10

A boilers that sit on 459-foot towers vents steam Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Some of the 300,000 computer-controlled mirrors, each about 7 feet high and 10 feet wide, reflect sunlight to boilers that sit on 459-foot towers. The sun's power is used to heat water in the boilers' tubes and make steam, which in turn drives turbines to create electricity Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Photo: Chris Carlson, AP

Some of the 300,000 computer-controlled mirrors, each about 7 feet...

Image 8 of 10

A boilers sits on 459-foot towers vents steam Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Photo: Chris Carlson, AP

A boilers sits on 459-foot towers vents steam Tuesday, Feb. 11,...

Image 9 of 10

A boilers sits on 459-foot towers vents steam Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

Photo: Chris Carlson, AP

A boilers sits on 459-foot towers vents steam Tuesday, Feb. 11,...

Image 10 of 10

Some of the 300,000 computer-controlled mirrors, each about 7 feet high and 10 feet wide, reflect sunlight to boilers that sit on 459-foot towers. The sun's power is used to heat water in the boilers' tubes and make steam, which in turn drives turbines to create electricity Tuesday, Feb. 11, 2014 in Primm, Nev. The Ivanpah Solar Electric Generating System, sprawling across roughly 5 square miles of federal land near the California-Nevada border, will be opened formally Thursday after years of regulatory and legal tangles.

On a desert plain not far from the Nevada border, vast fields of mirrors focus sunlight on three tall towers filled with water.

The intense light turns the water to steam. Pipes feed the steam through nearby turbines, generating enough electricity to power a small city.

Designed by BrightSource Energy in Oakland, the $2.3 billion Ivanpah Solar Electric Generating System, which officially enters operation Thursday, helps meet a goal pursued by California officials and private companies for more than a decade.

Yet BrightSource and other makers of solar power plants can't savor the moment for too long. Like any other business, they must find new customers.

Determined to fight global warming, the state in 2002 ordered its utilities to buy more renewable power, which prompted the construction of massive solar power plants, many located in the desert to tap the area's fierce sunshine. Those plants, meant to supply electricity to customers of Pacific Gas & Electric Co. and Southern California Edison, are now coming online.

More than enough

But California's utilities probably won't need more large solar power plants after the ones currently under development enter service. State law requires the utilities to get one-third of their electricity from renewable sources by the end of 2020. Ivanpah and the other projects under way should generate more than enough.

"The glory days, if you will, are behind us," said Tom Doyle, president of NRG Solar, the majority owner of Ivanpah. (Google also invested $168 million in the project.)

One possibility is to venture overseas. Doyle sees strong potential growth in Saudi Arabia, which has ambitious goals for using more solar power. BrightSource is pursuing projects in China, Morocco and South Africa.

States such as Georgia and Nevada have shown some interest as well.

In the end, the best opportunity for solar plant makers may still rest with California. Companies have been urging officials to raise the state's renewable power goals, perhaps to 50 percent. A law passed in Sacramento last year paved the way for such a step by giving state regulators the authority to raise the requirement on their own, without going through the Legislature first. But the timing and size of any increase - assuming it happens at all - remain uncertain.

"We're approaching a pretty big transition point here in California," said Arno Harris, CEO of Recurrent Energy in San Francisco. Recurrent develops utility-scale solar plants that, unlike BrightSource's, use photovoltaic cells to generate power. The company announced this month that it has completed six projects in California and Arizona, although all are much smaller than Ivanpah.

'The procurement of new projects has really slowed, almost to a standstill," Harris said. "This year is going to be a really big year for us, in terms of deciding our level of investment in California."

The cost of electricity from utility-scale solar plants that use photovoltaic panels has plunged in recent years, dropping nearly 48 percent since 2010, according to the U.S. Department of Energy. But it remains more expensive than electricity from standard power plants burning natural gas. Without some kind of government incentive driving the market, photovoltaic plants can't directly compete.

Price pressure

Some developers in California have proposed projects with electricity prices lower than those from natural gas plants, Doyle said. Many doubt whether they can deliver.

"One of the questions you have to ask is, are those real prices?" Doyle said.

Ivanpah uses a different technology known as "solar thermal" or "concentrating solar power." That technology isn't as widely used as photovoltaics, and it costs substantially more. One federal estimate, from early last year, suggested that electricity from a solar thermal plant cost 81 percent more than power from a photovoltaic facility, once equipment and construction costs were factored in.

BrightSource and other solar thermal developers say the technology has advantages that PV can't match. For example, solar thermal plants can more easily be paired with large-scale energy storage systems, allowing them to keep feeding electricity onto the grid after sunset. The Solana Generating Station that opened in October near Gila Bend, Ariz., uses molten salt to store energy in the form of heat.

Regardless of technology, utility-scale solar developers are under pressure to drum up new business as their current projects near completion. But BrightSource and other solar thermal developers may have a harder time of it, analysts say.

Last spring, the Oakland company canceled one of its planned California projects, dubbed Hidden Hills. And in December, the staff of the California Energy Commission recommended that the agency not approve BrightSource's next proposed power plant, the Palen Solar Electric Generating System in San Bernardino County. The staff cited the plant's potential danger to birds, which can be burned if they fly into the beams of concentrated sunlight.

'There's a path forward'

BrightSource hasn't given up on Palen. "We believe there's a path forward there," said Joe Desmond, the company's vice president of marketing and government affairs. The company built a plant in Coalinga (Fresno County) for a division of Chevron Corp. The plant generates steam to coax more oil out of an old oil field. (Chevron is one of BrightSource's investors.)